Robtex

Up: 103.15.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 103.15.40.0/23
Down right: 103.15.42.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
103.15.40.1	PTR	103.15.40.1-level3carrier.net
103.15.40.3	PTR	103.15.40.3-level3carrier.net
103.15.40.4	A+PTR	dns1.level3carrier.com
103.15.40.4	A+PTR	dns1.level3carrier.net
103.15.40.4	A	level3carrier.net
103.15.40.5	PTR	dns2.level3carrier.com
103.15.40.5	PTR	dns2.level3carrier.net
103.15.40.10	A+PTR	mail.level3carrier.net
103.15.40.10	PTR	mail.iconix.com.bd
103.15.40.10	A	mail.level3carrier.com
103.15.40.11	A+PTR	mrtg.level3carrier.com
103.15.40.150	A	level3carrier.net
103.15.41.66	A	ns1.level3carrier.com
103.15.41.209	PTR	103.15.41.209-level3carrier.net
103.15.41.209	A	scontent.fdac14-1.fna.fbcdn.net
103.15.41.210	PTR	103.15.41.210-level3carrier.net
103.15.41.210	A	video.fdac14-1.fna.fbcdn.net
103.15.41.218	A	gadgetstation.biz
103.15.41.222	A	sonar.fdac14-1.fna.fbcdn.net
103.15.41.224	A	z-p3-scontent.fdac14-1.fna.fbcdn.net
103.15.41.225	PTR	103.15.41.225-level3carrier.net
103.15.41.225	A	instagram.fdac14-1.fna.fbcdn.net
103.15.41.229	PTR	103.15.41.229-level3carrier.net
103.15.42.1	PTR	1-teletalk-gw.level3carrier.net
103.15.42.2	PTR	2-teletalk-peer.level3carrier.net
103.15.42.6	A+PTR	dns2.level3carrier.com
103.15.42.6	A+PTR	dns2.level3carrier.net
103.15.42.73	PTR	cache.google.com
103.15.42.76	PTR	cache.google.com
103.15.42.76	A	r1.sn-ax8xaj5ggpxg-q5je.gvt1.com
103.15.42.76	A	r1.sn-ax8xaj5ggpxg-q5je.googlevideo.com
103.15.42.77	PTR	cache.google.com
103.15.42.77	A	r2.sn-ax8xaj5ggpxg-q5je.googlevideo.com
103.15.42.78	PTR	cache.google.com
103.15.42.78	A	r3---sn-ax8xaj5ggpxg-q5je.googlevideo.com
103.15.42.79	PTR	103.15.42.79-level3carrier.net
103.15.42.81	PTR	103.15.42.81-level3carrier.net
103.15.42.81	A	r6---sn-ax8xaj5ggpxg-q5je.googlevideo.com
103.15.42.87	PTR	cache.google.com
103.15.42.88	PTR	cache.google.com
103.15.42.103	PTR	cache.google.com
103.15.42.113	PTR	103.15.42.113-level3carrier.net
103.15.42.116	PTR	cache.google.com
103.15.42.117	PTR	cache.google.com
103.15.42.141	PTR	cache.google.com
103.15.42.148	PTR	cache.google.com
103.15.42.151	PTR	cache.google.com
103.15.42.157	PTR	cache.google.com
103.15.42.158	PTR	103.15.42.158-level3carrier.net
103.15.42.179	PTR	cache.google.com
103.15.42.188	PTR	cache.google.com
103.15.42.198	A	mail.eximiusautomotive.com
103.15.42.198	A	mail.anassociatespartners.com
103.15.42.204	PTR	103.15.42.204-level3carrier.net
103.15.42.204	A	r1---sn-ax8xaj5ggpxg-q5jl.googlevideo.com
103.15.42.204	A	r1.sn-ax8xaj5ggpxg-q5jl.gvt1.com
103.15.42.205	PTR	103.15.42.205-level3carrier.net
103.15.42.205	A	r2.sn-ax8xaj5ggpxg-q5jl.gvt1.com
103.15.42.205	A	r2---sn-ax8xaj5ggpxg-q5jl.googlevideo.com
103.15.42.206	PTR	103.15.42.206-level3carrier.net
103.15.42.207	PTR	103.15.42.207-level3carrier.net
103.15.42.208	PTR	103.15.42.208-level3carrier.net
103.15.42.208	A	r5.sn-ax8xaj5ggpxg-q5jl.googlevideo.com
103.15.42.208	A	r5.sn-ax8xaj5ggpxg-q5jl.gvt1.com
103.15.42.209	PTR	cache.google.com
103.15.42.209	A	r6.sn-ax8xaj5ggpxg-q5jl.googlevideo.com
103.15.42.209	A	r6---sn-ax8xaj5ggpxg-q5jl.googlevideo.com
103.15.42.210	PTR	103.15.42.210-level3carrier.net
103.15.42.211	PTR	103.15.42.211-level3carrier.net
103.15.42.222	PTR	cache.google.com
103.15.42.227	PTR	cache.google.com
103.15.42.229	PTR	cache.google.com
103.15.42.241	PTR	cache.google.com
103.15.42.244	PTR	cache.google.com
103.15.43.1	PTR	103.15.43.1-nextonline.com.bd
103.15.43.98	PTR	103.15.43.98-nextonline.com.bd
103.15.43.102	PTR	peer.professionalsystem
103.15.43.138	A	www.smartitengineering.com
103.15.43.138	A	smitsol.com
103.15.43.138	A	www.smart-cms.org
103.15.43.200	PTR	user.exordonline
103.15.43.220	PTR	103.15.43.220-nextonline.com.bd
103.15.43.243	PTR	103.15.43.243-nextonline.com.bd